Field
The present invention relates to a fuel cell system, a fuel cell vehicle, and a method for evaluating an operational failure of an on-off valve equipped in the fuel cell system.
Related Art
In supplying hydrogen gas stored in a fuel tank to a fuel cell, the fuel cell system reduces the gas pressure to a predetermined supply pressure using a pressure control valve. For such decompression adjustment, there has been known a mouthpiece of a fuel gas tank having a pressure control valve and a pressure sensor built therein in addition to an on-off valve. Assuming such a structure, it is proposed to use the gas pressure detected by the pressure sensor at the tank mouthpiece for evaluating an operational failure of the pressure control valve or the on-off valve (see JP-2006-108024A, for example).
Since the evaluation method proposed in the patent literature referred to above assumes a single fuel tank, a similar evaluation method could not be applied to a configuration of multiple fuel gas tanks. This is because, if an operation is carried out where the fuel gas is supplied from multiple fuel gas tanks at the same time, the following problem is likely to occur: Assuming that all the outlet sides of the on-off valves in the multiple fuel gas tanks are converged co connect to the pressure control valve via a fuel supply pipe provided with a pressure sensor, it is hard to detect an opening failure of the on-off valve from sense cause at the tank mouthpiece of the fuel gas tank. This is because the fuel cell is supplied with fuel gas via a fuel supply pipe and the supplied gas pressure on time tank side upstream from the pressure control valve in the fuel supply pipe is sensed by the pressure sensor despite the fact that no fuel gas is supplied from the fuel gas tank with the faulty on-off valve at the tank mouthpiece. Then, the failure of the on-off valve, whether it be an opening failure or a shutting failure, cannot be judged simply by the supplied gas pressure on the tank side upstream from the pressure control valve in the fuel supply pipe, which lowers the reliability of the evaluation of a valve opening failure. For that reason, an evaluation method capable of preventing deterioration of reliability in evaluating the failure of on-off valves that open and shut the gas flow path from the fuel gas tank has been called in.